The commercial success of a resid-FCC catalyst relies on the ability of the catalyst to maintain activity and selectivity in the presence of contaminant metals. Resid feeds contain small amounts (e.g., 1-5 ppm) of contaminant metals that cumulatively deposit on the catalyst, result in high H2 and coke yields. Even small increases in the yields of these products relative to the yield of gasoline can cause significant practical problems. For example, in commercial refineries, expensive compressors are used to handle high volume gases, such as hydrogen. Therefore, an increase in the volume of hydrogen produced, can add substantially to the capital expense of the refinery. Nickel deposited on the resid-FCC catalysts from the feed is predominantly responsible for higher hydrogen and coke yields through catalysis of dehydrogenation reactions. In order to improve the performance characteristics of catalysts, reactive materials such as reactive alumina may be incorporated into FCC catalysts (e.g., crystalline boehmite) to maintain the activity and selectivity characteristics in the presence of contaminate metals. Alumina may react with NiO, resulting in the formation of NiAl2O4 that lowers dehydrogenation activity by preventing reduction of the nickel metal crystalline boehmite. Flex-Tech® by BASF Corporation, for example, is a modified microsphere catalyst having transition alumina derived from crystalline boehmite.
Other catalysts including boehmite are well known. For example, U.S. Pat. No. 4,789,654 to Hirano, et al. relates to a hydrocracking catalyst comprising a hydrogenating active component supported on a catalyst carrier consisting of a precursor of an alumina-containing inorganic oxide and a zeolite, where the alumina may be pseudoboehmite. However, such catalyst is not suitable for fluid catalytic cracking.
U.S. Pat. No. 7,208,446 to Stamires, et al. relates to a composition comprising a quasi-crystalline boehmite precursor and a zeolitic additive.
U.S. Pat. No. 6,403,526 to Lussier, et al. relates to a porous composite comprising gamma alumina, crystalline boehmite, and a crystal growth inhibitor.
PCT Publication No. WO1995/031280 to Shukis, et al. relates to a catalyst composition comprising a porous support of a gamma alumina, nanocrystalline alumina, and a catalytically active material.
U.S. Pat. No. 6,716,338 to Madon, et al. relates to a FCC catalyst comprising microspheres having in-situ zeolite and matrix made from boehmite and ultrafine kaolin.
U.S. Pat. No. 6,942,783 to Xu, et al. relates to a FCC catalyst with high porosity comprising boehmite and in-situ zeolite crystals distributed within calcined microspheres.
U.S. Pat. No. 6,673,235 to Harris, et al. relates to a FCC catalyst comprising macroporous matrix, in-situ crystallized zeolite, and transitional alumina.
However, boehmite samples from different suppliers are unexpectedly found to contribute to different catalytic performances when the boehmite samples are incorporated into FCC catalysts. Thus, there is a need for an improved FCC catalyst.